Currently only the server-side of Vaadin has been translated and Muntjac relies on the GWT compiled Java from Vaadin for the client code. The plan is to translate the rest and use Pyjamas to produce the JS. That way new components could be defined in Python.
You might want to try django-mediagenerator for Pyjamas integration. We already have a pyjs filter. See [1] for an example of how to use pyjs with mediagenerator.
You should be prepared for lots of subtle pyjs bugs, though. The translation isn't perfect. One problem is that the Pyjamas team is replicating GWT, so they only need a small subset of Python's features. They also don't use more advanced features for performance reasons. This means that many code paths are practically untested.
